Investigation of Factors Affecting Controlled Release from Photosensitive DMPC and DSPC Liposomes

Abstract

An investigation of liposomes comprised of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) lipids with cholesterol and zinc phthalocyanine (ZnPC) revealed that several fundamental liposome properties are influenced by composition and by lipid-specific features. DMPC and DSPC liposomes were synthesized, and their compositional changes, encapsulation capacities, morphologies, and release properties were evaluated. In this research, liposome degradation, lysis, and content release were initiated by photolysis, i.e., rupture induced by exposure to light. A controlled release mechanism was created through the introduction of photosensitizers (i.e., ZnPC) embedded within the cholesterol-stabilized liposome membrane. The light wavelength and light exposure time accelerated photodegradation properties of DMPC liposomes compared to DSPC liposomes, which exhibited a slower release rate. Morphological changes in the liposomes were strongly influenced by light wavelength and light exposure time. For both the DMPC and DSPC liposomes, visible light with wavelengths in the red end of the spectrum and broad spectrum ambient lighting (400-700 nm) were more effective for lysis than UV-A light (365 nm). Heating liposomes to 100 °C decreased the stability of liposomes compared to liposomes kept at room temperatures. In addition, the optimal lipid-to-cholesterol-to-photoactivator ratio that produced the most stable liposomes was determined.

Statistical optimization of tretinoin-loaded penetration-enhancer vesicles (PEV) for topical delivery

“…The phase transition temperature (T m ) of the lipids affected the release of liposome [ 24 ]. Phospholipids at their T m changed from solid to liquid state.…”

Stimuli‐responsive liposomes for drug delivery

“…Zinc phthalocyanine (ZnPC) has been used to photosensitize controlled release from liposomes. ZnPC‐liposomes containing DMPC or DSPC showed various release trends for a reporter (ONPG) with different exposure light type (20% for red (640 nm, 160 mW/cm 2 ), >13% for ambient (400–700 nm, 5.6 mW/cm 2 ), and >2% for UV‐A light (~365 nm, 50 mW/cm 2 ) after 24 h . In addition, the palladium‐based phthalocyanine PS, PdPC(OBu) 6 , was used in a liposomal formulation to provide on‐demand local anesthesia by delivering tetrodotoxin (TTX) upon near‐infrared radiation (NIR).…”

Therapeutic efficacy of doxorubicin delivery by a CO2 generating liposomal platform in breast carcinoma

“…Although liposomes provide a promising chemotherapeutic strategy, their use in clinical trials for controlled drug release has been limited. To overcome the limitations associated with the use of liposomes, surface modification by polymers [3,4] and external stimulation-triggered drug release strategies [5] have been employed to develop advanced liposomal formulations, such as pH- [6,7], ultrasound- [8,9], and light-sensitive liposomes [10,11], for increased drug release at the target site. Although advanced liposomal systems have been developed to increase drug release within tumor tissue, the factors determining the optimum formulation and control of drug release for effective chemotherapy are not well understood.…”